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From: Pavel Holejsovsky <pavel DOT holejsovsky AT upek DOT com>
Subject: Re: R: getsockopt(SO_KEEPALIVE) returns incorrect option length
Date: Fri, 02 Jul 2010 13:31:54 +0200
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On 7/2/2010 12:01 PM, Marco Atzeri wrote:
> --- Ven 2/7/10, Pavel Holejsovsky ha scritto:
>
>> Hi,
>>
>> I think that following problem shows problematic behavior
>> in cygwin 1.7.5, at least incompatible with linux:
>>
>> #include<stdio.h>
>> #include<sys/socket.h>
>>
>> int main() {
>>          int sock, option, optlen =
>> sizeof(int);
>>          sock = socket(AF_INET,
>> SOCK_STREAM, 0);
>>          getsockopt(sock, SOL_SOCKET,
>> SO_KEEPALIVE,&option,&optlen);
>>          printf("option=%d,
>> optlen=%d\n", option, optlen);
>>          return 0;
>> }
>>
>> Prints optlen=1, while it is expected to be sizeof(int),
>> i.e. 4.
>>
>> This is most probably because uinderlying winsock call has
>> this (mis)behavior, but I think that in cygwin layer this
>> could be worked around to be more unix compatible.
>>
>> This issue is relevant:
>>
>> SO_KEEPALIVE value is actually a char on Windows, not BOOL
>> https://bugzilla.gnome.org/show_bug.cgi?id=611756
>>
>> And causes glib gio 2.24 to fail certain socket operations
>> on cygwin.
>>
>> thanks,
>> Pavel
>
> option=0, optlen=4
>
> on XP-sp2, cygwin 1.7.5s(0.227/5/3) 20100628
>

Thanks for testing, Marco.

So it is even system-dependent misbehaviour of winsock.  On w7-x64 
cygwin 1.7.5 it prints
option=2674688, optlen=1

Pavel


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